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CONTRIBUTIONS  FROM  THE  ZOOLOGICAL  LABORATORY  OF  THE 
MUSEUM  OF  COMPARATIVE  ZOOLOGY  AT  HAIiVARI) 

COLLEGE.  E.  L.  MARK,  Director.  * v t 

2)' 


No.  1G3. 


~flcdC^ 


phosphorescence:  in  ctenophores. 


By  Amos  W.  Peters. 


From  the  Journal  of  Experimental  Zoology,  Vol.  II,  No.  1. 


CAMBRIDGE,  MASS.,  U.  S.  A. 
April,  1905. 


I 


Digitized  by  the  Internet  Archive  , 

in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates  I 

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https://archive.org/details/phosphorescenceiOOpete 


CONTRIBUTIONS  FROM  THF  ZOOLOGICAL  LABORATORY  OF  THK  MUSKUM 
I OF  COMPARATIVE  ZOOLOGY  AT  HARVARD  COLLEGE.  E.  L.  MARK, 
j Dirkctor. — No.  163. 


PHOSPHORESCENCE  IN  CTENOPHORES. 

liY 


AMOS  PETERS. 


INTRODUCTION. 


The  problems  discussed  in  this  paper  are  the  localization  of  the 
power  of  phosphorescence  in  mature  and  in  young  ctenophores, 
nd  the  influence  of  certain  factors,  such  as  mechanical  stimula- 
tion, light,  and  heat,  upon  the  ability  of  these  animals  to  phos- 
phoresce. 

The  species  upon  which  I have  worked  is  the  common  summer 
ctenophore,  Mnemiopsis  leidyi  A.  Agassiz.  These  animals  were 
to  be  found  at  Wood’s  Hole,  Mass.,  abundantly  during  August, 
1902  and  1903.  The  phenomenon  of  phosphorescence  which 
they  exhibited  in  their  native  sea-water  when  mechanically 
agitated  after  dark  was  suggestive  of  laboratory  experiments. 

In  my  experiments  I found  it  necessary  to  use  a dark  chamber, 
which  I constructed  from  a simple  pine  box  heavily  covered  first 
‘with  paper  and  then  with  several  layers  of  black  cloth.  The  dark 
box  was  placed  upon  a table  before  the  experimenter  and  its  open 
front  was  provided  with  overhanging  cloth,  sufficient  to  include 
his  head  and  shoulders.  This  arrangement  permitted  both  the 
^observation  of  phosphorescence  and  the  free  use  of  the  experi- 
nienter’s  hands  for  agitating  the  ctenophores,  etc.  This  appara- 
tus was  not  quite  as  efficient  as  a dark  room,  yet  it  was  adequate 
fc>r  the  work  that-  was  attempted  in  it.  As  observation  of  the 
animals  required  the  continuous  attention  of  the  experimenter  in 
,tl.e  dark-box  and  as  light  must  be  excluded,  the  time  was  read  and 
rr  corded  by  an  assistant  upon  signals  from  the  experimenter. 
1 his  procedure  also  favored  the  adjustment  of  the  experimenter’s 
eye  to  the  conditions  of  observation  after  the  change  from  daylight 
to  darkness.  The  time  here  recorded  was  read  to  tenths  of  a 
minute,  and  differences  so  small  as  this  are  nowhere  of  conse- 


104 


Amos  W.  Peters. 


quence  in  the  following  work.  The  abundance  ot  the  material 
made  it  possible  to  select  animals  of  the  same  large  size  for  most 
of  the  experiments.  Lots  of  from  four  to  eight  were  placed  in 
glass  or  porcelain  dishes  containing  about  one  liter  of  sea-water 
brought  in  with  the  animals.  In  these  dishes  most  of  the  test  s 
for  phosphorescence  were  made. 

Several  methods  of  mechanical  stimulation,  to  be  used  in  testing 
the  animals  for  phosphorescence,  were  tried  and  compared.  The 
most  efficient  of  these  was  stirring  the  ctenophores  by  means  of  a 
glass  rod.  Simple  contact  with  the  rod  frequently  succeeded  in 
bringing  forth  the  response  of  phosphorescence  when  jarring, 
shaking,  etc.,  failed.  The  adult  animals  being  of  sufficient  size 
and  weight,  the  contact  of  the  glass  rod  with  them  was  easily 
perceptible  through  the  skin  and  muscles  of  the  experimenter  in 
the  dark.  This  method  of  stimulation  was  uniformly  adopted  rs 
a standard  in  this  work,  being  also  used  for  small  parts  of  animals, 
embryos,  and  eggs.  Unless  a statement  to  the  contrary  is  mad(S 
a fresh,  previously  unused  lot  of  ctenophores  was  used  in  eaca 
test. 

Strict  uniformity  of  conditions  and  the  constant  presence  of 
control  animals  excluded  from  the  observations  here  recorded, 
it  is  hoped,  errors  arising  from  insufficient  adjustment  of  the 
eye  as  well  as  from  other  sources.  That  these  experiments 
could  profitably  be  repeated  and  extended  with  a much  grean^r 
degree  of  refinement,  is  a point  the  writer  desires  to  emphasize. 

He  wishes  to  express  here  his  indebtedness  to  Dr.  G.  H.  Parker, 
of  Harvard  University,  for  critical  advice  and  suggestion,  and  for 
the  revision  of  the  manuscript.  He  is  also  under  obligation  to  the 
Humboldt  Fund  of  the  Museum  of  Comparative  Zoology  at 
Harvard  College  for  financial  assistance.  Furthermore,  his 
thanks  are  due  to  the  authorities  of  the  United  States  Fish  Com- 
mission for  the  use  of  its  laboratory  at  Wood’s  Hole,  Mass., 
during  the  summers  of  1902  and  1903. 

II.  LOCALIZATION  OF  PHOSPHORESCENCE. 

I.  In  Mature  Animals. 

As  is  well  known,  ctenophores  brought  into  the  laboratory 
disintegrate  quite  readily.  The  dead  substance  of  such  animrls 
was  frequently  tested  both  in  the  dark-hox  and  in  the  dark-room 


Phosphorrscriice  in  (Jfcnophores.  105 

In  no  case  was  any  phospliorescence  detected  in  the  dead  matter 
originating  from  ctenopliores. 

It  was  observed  that  after  rough  weather  many  ctenophores 
were  mutilated  hut  nevertheless  phosphorescent.  Even  separated 
pC)rtions  of  the  animal  show  this  reaction  both  in  the  sea  and  in  the 
laooratory.  Such  pieces  examined  under  the  magnifier  always 
showed  movements  of  the  paddle  plates  and  frequently  muscular 
contraction.  In  short,  the  pieces  of  the  animal  were  found  to  be 
alve.  All  the  observations  made  gave  the  result  that  only  the 
In  ing  ctenophores  or  living  parts  of  them  phosphoresce. 

When  either  whole  ctenophores  of  small  size,  or,  much  better, 
excised  parts  from  various  regions  of  the  animal  were  examined 
under  the  magnifier  in  the  dark,  phosphorescence  seems  to  be 
piesent  only  along  the  rows  of  paddle  plates.  When  the  paddle 
pi  ites  were  numerous  upon  the  excised  piece,  adjacent  parts  were 
often  so  illuminated  as  to  make  this  determination  uncertain. 
But  when  portions  of  the  jelly  entirely  free  from  paddle  plates 
Were  examined  no  phosphorescence  was  seen.  Such  jelly  was 
alive,  for  when  the  same  preparation  was  examined  in  the  daylight 
muscular  contraction  could  be  seen  in  it.  In  the  course  of  these 
experiments  no  phosphorescence  could  be  obtained  from  jelly 
frqe  from  paddle  plates. 

The  smallest  piece  from  which  phosphorescence  was  obtained 
consisted  of  four  connected  paddle  plates  with,  of  course,  some 
jelly  adhering.  Even  single  excised  paddle  plates  were  observed 
to  live  for  many  hours  or  a day,  as  judged  by  their  motion,  and 
yet;  all  efforts  to  get  phosphorescence  from  single  excised  paddle 
plrtes  were  unsuccessful. 

The  excised  auricles  showed,  under  the  magnifier,  cilia  but  no 
pjaddle  plates.  No  phosphorescence  was  obtained  from  them. 

^ ! The  sense  organ  with  adjacent  parts  was  excised  in  a piece  about 
two  centimeters  long  and  one  centimeter  broad.  Under  the 
uiagnifier  no  paddle  plates  were  seen,  but  muscular  contraction 
W as  evident.  No  phosphorescence  could  be  obtained  from  such 
a piece. 

The  previously  described  experiments  with  excised  rows  of 
paddle  plates,  or  parts  of  them,  are  sufficient  to  show  that  phos- 
phorescence does  not  depend  upon  correlation  of  the  part  with  the 
simse  organ.  Whether  cut  in  two  transversely,  or  longitudinally 
ir  such  a manner  as  to  leave  the  sense  organ  wholly  in  one  part. 


io6 


A mos  fV.  Peters. 


the  result  was  the  same.  In  both  cases  the  piece  without. the 
sense  organ,  as  well  as  that  with  it,  was  phosphorescent. 

If  the  whole  animal  had  been  made  phosphorescent  in  the  dark- 
box  before  the  operation,  both  pieces  retained  phosphorescence; 
if  the  whole  animal  was  originally  non-phosphorescent,  the  pieces 
acquired  this  property  in  the  dark-box. 

Numerous  tests  were  made  to  determine  whether  after  trans- 
verse or  longitudinal  division  the  piece  retaining  the  sense  organ 
acquired  phosphorescence  sooner  or  later  than  the  other  piece. 
A normal  animal,  as  a check,  was  subjected  to  the  same  test  at  the 
same  time.  The  results  seemed  to  follow  the  law  of  chance. 
Sometimes  the  piece  with  the  sense  organ  phosphoresced  more 
quickly  than  the  other,  sometimes  more  slowly.  The  results 
were  hence  negative  and  warrant  the  statement  that  the  sense 
organ  is  not  a controlling  center  for  phosphorescence. 

It  was  now  clear  that  phosphorescence  was  localized  somewhere 
in  or  near  the  paddle  plates,  and  that  the  reaction-chain  from 
stimulation  to  response  consists  very  probably  of  an  anatomically 
short  and  entirely  local  series  of  elements,  i.  ^.,  there  is  no  dista  nt 
central  station  for  the  reception,  modification,  or  dispatch  of 
impulses.  Although  it  was  shown  that  phosphorescence  bears  a 
local  relation  to  the  paddle  plates  the  question  was  still  opc^n 
whether  any  necessary  relation  existed. 

The  attempt  was  therefore  made  to  ascertain  by  experime  nt 
whether  all  movement  of  the  paddle  plates  are  accompanied  w th 
phosphorescence.  A glass  evaporating  dish  eight  .inches  in 
diameter  and  three  inches  in  depth  was  filled  with  sea-water  to 
within  half  an  inch  of  the  top.  At  night  a single  medium-si;  ed 
and  strongly  phosphorescent  ctenophore  was  placed  in  the  dish  in 
the  dark-room.  The  whole  was  left  undisturbed  for  some  time 
to  insure  the  absence  of  currents  originating  from  external  me- 
chanical disturbance  of  the  dish.  At  intervals  the  dark-room  wrts 
sufficiently  illuminated  to  enable  the  observer  to  note  the  position 
of  the  animal  in  the  dish.  During  the  dark  periods  the  attention 
of  the  experimenter  was  directed  upon  the  dish  for  the  purpose  of 
observing  phosphorescence,  if  any  occurred.  The  result  was  thot 
though  the  ctenophore  was  almost  constantly  changing  position, 
sometimes  to  the  extent  of  half  the  diameter  of  the  dish,  yet  it 
showed  no  phosphorescence  during  the  great  majority  of  the  dark 
intervals.  Evidently  during  such  intervals  the  paddle  plates  e 


107 


J^hosphorescnicr  iii  C'Jctiopborcs. 

in  motion  and  yet  without  being  accompanied  by  phosphorescence. 
When  in  a dark  period  phosj)liorescence  was  seen,  the  light  was 
immediately  turned  on,  and  it  was  observed  that  the  ctenophore 
was  adjacent  to  the  side  of  the  dish  and  had  probably  struck  it  in 
the  course  of  locomotion.  A slight  mechanical  stimulus,  such  as 
touching  the  animal  with  a glass  rod,  jarring  the  dish,  or  the  table 
upon  which  it  was  placed,  easily  elicited  the  response  of  phos- 
phorescence, both  before  and  after  the  experiment  described 
above.  It  was  clear  that  the  animal  was  capable  of  phosphores- 
cence during  all  the  periods  of  locomotion,  but  the  necessary 
mechanical  stimulus  was  absent  except  when  the  ctenophore  came 
into  contact  with  the  side  of  the  dish. 

2.  In  Embryos. 

Further  observations  were  directed  toward  finding  how  far 
back  in  the  ontogeny  of  the  animal  phosphorescence  could  be 
traced.  The  eggs  were  obtained  as  follows:  On  August  6,  some 
ctenophores  were  brought  into  the  laboratory  and  placed  in  glass 
evaporating  dishes  each  containing  about  two  liters  of  the  sea- 
water brought  in  with  them.  Two  animals  were  placed  in  each 
dish.  The  water  was  changed  once  or  twice,  only  such  being 
used  as  was  brought  directly  from  the  sea.  On  the  morning 
of  August  7,  a layer  of  eggs  in  various  stages  of  development  was 
found  upon  the  bottom  of  each  dish.  By  withdrawing  the  sea- 
water above  them  and  replacing  it  with  fresh  sea-water  about 
twice  a day,  they  were  reared  to  fully  formed  young  ctenophores. 
In  no  instance  were  eggs  observed  to  be  deposited  in  the  day  time. 

When  a lot  of  eggs  had  developed  to  the  stage  in  which  the  four 
sets  of  paddle  plates  first  appear,  phosphorescence  could  be 
demonstrated.  If  at  night  the  embryos  were  stirred  with  a glass 
rod,  or  the  dish  containing  them  was  jarred,  numerous  phos- 
phorescent specks  would  appear  momentarily.  The  experiment 
did  not  easily  succeed  in  the  day  time,  even  if  the  eggs  were  kept 
in  the  dark-room.  Perhaps  the  same  rhythm  in  the  intensity  of 
phosphorescence  belongs  to  them  as  to  the  adults.  In  the  latter 
it  was  observed  (1903)  that  phosphorescence  was  more  intense 
and  more  easily  excited  at  night  than  during  the  daytime,  even 
when  the  animals  were  kept  continuously  in  the  dark-room. 
Furthermore,  the  phosphorescence  of  these  embryos  could  not  be 
indefinitely  repeated,  but  was  exhausted  after  a few  flashes.  In 


o8 


A mos  JV.  Peters. 


this  respect  also  they  resemble  the  adults,  except  that  exhaus:ion 
is  much  more  quickly  produced. 

Experiments  were  made  to  test  for  phosphorescence  before  the 
formation  of  the  paddle  plates.  A single  gastrula  was  isolated 
at  night  in  a watch  glass.  It  was  still  contained  in  the  egg- 
capsule  and  showed  ciliary  movement  but  no  paddle  plates  were 
as  yet  developed.  It  was  placed  in  the  dark-room  and,  to  make 
the  conditions  as  favorable  for  the  reaction  as  possible,  it  was 
allowed  to  remain  undisturbed  for  half  an  hour,  when  the  watch 
glass  was  suddenly  jarred  and  a flash  resulted.  Another  flash 
could  not  be  obtained  until  after  a period  of  rest. 

Experiments  were  next  made  to  test  for  phosphorescence  in  the 
segmentation  stages  and  in  the  egg.  It  had  been  several  times 
observed  during  these  studies  that  embryos  from  animals  that  had 
been  kept  in  the  dark-room  during  the  previous  day  were  further 
advanced  when  examined  the  next  morning  than  the  embryos 
from  animals  kept  in  diffuse  daylight  during  the  previous  day. 
Both  lots  originated  from  the  same  collection  and  were  parallel 
in  conditions  except  with  regard  to  light.  In  this  experiment  the 
influence  of  light  upon  the  time  of  egg  laying  was  also  tested. 

August  II,  1903,2  p.  m.  Collected  Mnemiopsis.  Distribu  ed 
them  into  lots  A and  B,  each  consisting  of  several  dishes.  A was 
kept  in  the  dark-room.  B remained  in  diffuse  daylight,  later  in 
artificial  light,  electricity  and  gas. 

10  p.  m.  No  eggs. 

1 1. 1 5 p.  m.  Eggs  present  in  lot  A of  the  dark-room.  No  eggs 
in  lot  B. 

A number  of  eggs  were  immediately  isolated  in  a solid  watch 
glass  and  tested  by  stirring  with  a glass  rod  and  by  jarring,  at 
intervals,  in  the  dark-room.  They  were  examined  before  and 
after  the  series  of  tests  and  were  found  to  consist  of  one-cell 
stages.  No  phosphorescence  could  be  detected  in  these  undivided 
eggs. 

August  12,  12.20  a.  m.  Cleavage  stages  from  lot  A were  iso- 
lated in  a solid  watch  glass.  Examination  before  and  after  the 
tests  showed  that  no  ciliated  (moving)  embryo  was  as  yet  formc'd. 
Stages  from  one  to  thirty-two  cells  were  present.  After  an  undis- 
turbed period  in  the  dark-room  stirring  with  a glass  rod  elicited 
phosphorescent  flashes,  but  probably  not  from  all  the  eml-ryos. 
12.45  ^gg^ 


Phosphorrscnicr  in  (Ucno pJjores . 1 09 

1.20  a.  ni.  Many  embryos  in  lot  A were  becoming  gastrul^c. 
Also  many  undeveloped  (dead  ?)  one-cell  stages  were  still  present 
in  lot  A. 

^ 1.30  a.  m.  No  eggs  in  lot  B. 

2.20  a.  m.  Some  esss  in  lot  B.  Some  of  these  were  isolated 
in  solid  watch  glasses,  examined  before  and  after  testing  for 
phosphorescence  and  found  to  be-in  one-cell  stages. 

2.40  a.  m.  No  phosphorescence  was  detected  in  the  one-cell 
stao-e  isolated  above  from  lot  B. 

An  interesting  result  of  this  experiment  is  the  difference  of 
about  three  hours  in  the  time  of  the  laying  of  the  eggs  between 
lots  A and  B;  lot  A having  been  in  the  dark  longer,  deposited  eggs 
sooner.  In  a subsequent  experiment  it  was  observed  that  animals 
kept  in  the  dark  from  9 a.  m.  had  not  yet  deposited  eggs  at  10.30 
p.  rn.,  although  eggs  were  present  the  next  morning.  Hence  the 
deposition  of  eggs  does  not  seem  to  occur  after  simply  a given 
number  of  hours  of  darkness.  The  indications  favor  the  view 
that  the  deposition  of  eggs  takes  place  in  accordance  with  the 
daily  rhythm  of  light  and  darkness,  deposition  occurring  in  the 
dark  period,  and  being  capable  of  retardation  by  light. 

III.  INFLUENCE  OF  CERTAIN  FACTORS  ON  PHOSPHORESCENCE. 

I.  Agitation  and  Light. 

In  determining  what  factors  influence  phosphorescence  it  has 
been  found  convenient  to  deal  with  agitation  and  light  together. 
Preliminary  tests  showed  that  ctenophores  removed  to  the  dark- 
box  at  once  from  their  native  sea-water,  where  they  had  been 
exposed  to  direct  sunlight,  were  not  immediately  phosphorescent. 
However,  they  became  so  after  remaining  in  the  dark  for  some 
time.  Similar  observations  were  first  made  on  Beroe  by  Allman 
(’62)  and  subsequently  by  Panceri  (’72).  The  above  fact  was  the 
starting  point  for  a series  of  experiments  in  which  both  light  and 
agitation  were  factors. 

Experiment  I.  Lots  A and  B having  been  exposed  to  direct 
sunlight  for  about  one  hour,  were  both  placed  in  the  dark-box  at 
the  same  time.  The  ctenophores  in  A were  then  continually 
agitated  with  a glass  rod,  while  B was  left  undisturbed  except  for 
momentary  tests  made  at  intervals.  A phosphoresced  first  in 
2.5  minutes;  B in  3.0  minutes. 


1 10 


A mos  fV.  Peters. 


The  result  shows  that  direct  sunlight  prevents  the  occurrence  of 
phosphorescence  and  that  mechanical  stimulation  accelerates  it. 

Experimej^t  2.  Two  phosphorescent  lots,  A and  B,  were 
exposed  to  direct  sunlight  for  three  minutes.  They  were  then 
both  placed  in  the  dark-box  at  the  same  time.  They  were  both 
found  to  be  non-phosphorescent.  A was  then  continuously 
agitated  and  B was  left  undisturbed  except  for  tests,  as  above 
described.  A phosphoresced  first  in  2.5  minutes;  B in  3.0  min- 
utes. 

After  permitting  the  phosphorescence  to  develop  for  a minute 
or  two,  A was  exposed  to  direct  sunlight  for  two  minutes  while 
B remained  in  diffuse  daylight.  A was  continually  agitated  in 
the  dark-box  as  above  described.  A phosphoresced  first  in  i 
minute;  B continued  to  phosphoresce. 

After  some  minutes  both  were  exposed  to  diffuse  daylight  and 
then  tested  as  follows:  A was  agitated  in  the  dark-box,  while  B 
remained  undisturbed.  A first  phosphoresced  in  i minute;  B in 
2 minutes. 

The  result  indicates  that  exposure  to  direct  sunlight  not  only 
prevents  phosphorescence,  as  found  in  the  preceding  experiment, 
but  also  overcomes  a previously  acquired  power  to  phosphoresce. 
Furthermore  mechanical  stimulation,  as  before,  accelerates  the 
appearance  of  phosphorescence. 

Experiment  3.  ’It  was  observed  that  Mnemiopsis  was  some- 
times phosphorescent  and  sometimes  not  so  after  standing  for  a 
time  in  the  diffuse  daylight  of  the  laboratory.  The  object  of  this 
experiment  was  to  test  the  power  of  diffuse  daylight,  of  the  inten- 
sity then  prevailing  in  the  laboratory,  to  inhibit  or  permit  phos- 
phorescence, as  well  as  to  test  further  the  influence  of  mechanical 
stimulation.  The  ctenophores  used  had  been  exposed  to  diffuse 
daylight.  A was  agitated  in  the  dark-box,  but  B,  in  the  same 
box,  was  undisturbed  except  for  tests.  Both  A and  B were  thien 
again  exposed  to  diffuse  daylight.  A was  then  put  in  the  dark- 
box  and  agitated;  B was  undisturbed  except  for  tests.  A phos- 
phoresced first  in  1.7  minutes;  B in  2.5  minutes. 

The  results  show  that  diffuse  daylight  can  check  phosphores- 
cence and,  as  before,  mechanical  stimulation  can  accelerate  its 
appearance. 

Experiment  p.  In  this  experiment  ctenophores  in  the  dark-hox 
were  continuously  agitated  with  a glass  rod  to  determine  wheth<  r 


Phosphorrscciice  in  (Pcnophorcs. 


I I I 


the  phosphorescent  condition  could  he  removed  by  excessive 
mechanical  agitation.  Reduction  of  intensity  had  frequently 
been  observed  after  long  continued  agitation. 

2.22  p.  m.  Strong  phosphorescence. 

2.42  p.  m.  Phosphorescence  appears  only  in  slight  gleams,  but 
these  persist  upon  stimulation  'with  the  glass  rod. 

The  result  indicates  that  sufficiently  long-continued  agitation 
reduces  the  intensity  of  phosphorescence,  but  does  not  entirely 
inhibit  it. 

Experiment  The  object  of  this  experiment  'was  to  determine 
whether  the  rate  at  which  the  ability  to  phosphoresce  is  acquired, 
varies  with  the  intensity  of  the  light.  Lots  A and  B each  with  six 
ctenophores,  were  exposed  to  direct  sunlight  for  five  minutes. 
The  temperature  of  the  sea-water  before  the  exposure  was  21^.5 
C.;  after  it,  22^.5  C.  Then  A was  kept  in  the  dark-box  until 
phosphorescent,  being  tested  at  intervals  (/.  ^.,  not  continuously 
agitated).  During  the  same  time  B was  exposed  to  diffuse  day- 
light and  at  intervals  it  was  placed  in  the  dark-box  for  a momen- 
tary test.  B did  not  phosphoresce  during  the  whole  experiment 
(19.5  minutes).  A phosphoresced  first  after  three  minutes  in  the 
dark-box,  and  though  kept  in  diffuse  daylight,  it  retained  its 
phosphorescence  over  five  minutes,  after  which  it  lost  its  phos- 
phorescence so  long  as  it  remained  in  the  light. 

The  result  indicates  that  the  ability  to  phosphoresce  is  acquired 
more  quickly  in  darkness  than  in  diffuse  daylight  and  also  that 
phosphorescence  has  a proportionate  relation,  in  a negative  sense, 
to  the  intensity  of  the  light. 

Experiment  6.  Preceding  experiments  have  shown  that:  (i) 
darkness  is  at  least  one  necessary  condition  for  phosphorescence; 
(2)  darkness  alone  does  not  result  in  phosphorescence;  and  (3) 
mechanical  agitation  can  caii  u'rth  and  accelerate  this  phenom- 
enon in  the  dark.  This  compai  son  suggested  the  question.  Can 
agitation  alone  produce  phosphorescence  ^ To  make  this  deter- 
mination a lot  of  ctenophores  were  poured  repeatedly  from  one 
dish  to  another  in  diffuse  daylight  and  were  tested  at  intervals  in 
the  dark-box.  The  agitation  including  the  tests  was  continued 
for  a period  of  ten  minutes.  No  phosphorescence  whatever  could 
be  detected.  The  inability  of  agitation  to  produce  this  phenom- 
enon was  frequently  observed. 


I 12 


A rnos  JV.  Peters. 


This  result  shows  that  a non-phosphorescent  ctenophore  is  not 
made  phosphorescent  by  mechanical  agitation  alone.  Further- 
more, comparison  of  all  preceding  experiments  shows  that  dark- 
ness accompanied  by  mechanical  stimulation  is  at  least  one  com- 
bination of  conditions  which  is  able  to  produce  phosphorescence, 
but  its  two  factors  acting  singly  cannot  produce  this  result. 
Other  stimuli  capable  of  eliciting  phosphorescence  may,  of  course, 
exist. 

2.  T emperature. 

Experiment  /.  This  experiment  was  made  to  determine  the 
effects  of  physiological  extremes  of  temperature.  It  was  per- 
formed in  a dark  room.  A pailful  of  fresh  ctenophores  standing 
there  at  a temperature  of  21^.5  C.  emitted,  when  jarred,  enough 
light  to  illuminate  the  room  to  a considerable  degree.  From  this 
supply  four  animals  (lot  A)  were  removed  to  the  ice  bath  and  four 
others  (lot  B)  to  the  warm-water  bath.  The  respective  cooling 
and  warming  of  the  two  lots  was  done  simultaneously.  The  ice 
bath  consisted  simply  of  a basin  containing  broken  ice,  in  which 
the  vessel  containing  lot  A was  partly  immersed.  Neither  ice  nor 
fresh  water  (from  melting  ice)  came  into  contact  with  the  animals. 
They  were  gradually  cooled  in  their  original  sea-water.  The 
other  lot  of  animals  (B)  were  warmed  in  sea-water  by  placing  the 
vessel  containing  them  over  sufficiently  warmed  water.  The  tests 
for  phosphorescence  were  made  at  intervals  by  stroking  the 
ctenophores  as  usual  with  a glass  rod.  The  temperatures  were 
taken  with  the  bulb  of  the  thermometer  in  contact  with  the  surface 
of  the  animal.  Since  the  phosphorescent  parts,  the  paddle  plates, 
are  superficial,  the  temperatures  given  apply  to  these  parts.  The 
interior  of  the  jelly  might  have  been  at  a different  temperature. 
Under  these  conditions  the  following  record  was  obtained: 

Lot  A at  2i°.5  C.  was  strongly  phosphorescent;  seven  minutes 
later  at  12°. 5 C.  no  phosphorescence  could  be  observed.  A was 
then  removed  to  the  warm-water  bath  whereupon  the  animals 
became,  after  some  time,  phosphorescent.  Hence  the  previous 
cessation  of  phosphorescence  was  not  due  to  death. 

Lot  B at  21°. 5 C.  was  also  strongly  phosphorescent;  five  min- 
utes later  at  37°  C.  no  phosphorescence  was  observable. 


PJjos phorcsccncc  in  (Ucnophores.  i 13 

Lot  13  was  then  removed  to  the  ice  bath  whereupon  the  animal 
became,  after  some  time,  phosphorescent.  Hence  the  previous 
cessation  of  phosphorescence  was  not  due  to  death. 

Experiment  2.  The  aim  and  methods  of  this  experiment  were 
the  same  as  in  Experiment  i. 

Lot  A at  21^.5  C.  was  strongly  phosphorescent;  after  6.5  min- 
utes cooling  it  was  much  diminished,  and  after  13.5  minutes 
(9°  C.)  there  was  no  phosphorescence.  Lot  A was  then  placed 
on  the  warm  water-bath  and  in  13  minutes  became  again  phos- 
phorescent. 

Lot  B at  21^.5  C.  was  strongly  phosphorescent;  after  seven 
minutes  warming  the  phosphorescence  was  much  diminished,  and 
after  ten  minutes  (38°  C.)  there  was  none.  At  this  temperature 
the  animals  had  completely  disintegrated. 

Experiment  The  aim  and  methods  of  this  experiment  were 
the  same  as  in  Experiments  i and  2. 

Lot  A,  strongly  phosphorescent  at  21°. 5 C.,  was  cooled  in  ten 
minutes  to  9^.5  C.  and  became  non-phosphorescent. 

Lot  B,  strongly  phosphorescent  at  21^.5  C.,  was  cooled  in  12.5 
minutes  to  1 1^.5  C.  and  became  non-phosphorescent. 

Another  series  of  experiments  was  made  to  determine  the  effects 
of  variations  of  a few  degrees  only  from  the  normal.  Such  varia- 
tions, of  from  one  to  four  degrees  above  and  below  the  normal 
(2i°.5  C.),  showed,  in  all  the  trials  but  one,  a diminution  of  phos- 
phorescence as  compared  with  a control.  In  other  words,  phos- 
phorescence in  the  dark-box  appeared  sooner  in  the  animals  at 
normal  temperature  than  at  any  other  temperature.  It  would 
not  have  been  surprising  to  find  an  optimum  point  slightly  differ- 
ent from  the  normal  temperature.  The  experiments  made  upon 
this  subject  are  not  regarded  as  conclusive. 

The  general  result  of  this  work  upon  temperature  may  be 
stated»as  follows: 

The  phenomenon  of  phosphorescence  in  the  ctenophores  here 
investigated  occurred  during  a range  of  temperature  extending 
from  about  9°  C.  to  37°  C.,  with  an  optimum  at  or  near  2I°.5  C., 
which  was  the  temperature  of  their  native  sea-water.  The  inten- 
sity of  phosphorescence  diminishes  as  physiological  extremes  of 
temperature  are  approached. 


Amos  JV.  Peters. 


114 


IV.  DISCUSSION  OF  RESULTS. 

The  preceding  experiments  demonstrate  that  the  power  of 
phosphorescence  is  located  in  the  mature  animal  solely  in  the 
region  of  the  paddle  plates.  I am  not  aware  of  direct  evidence 
for  a more  precise  localization  than  that  just  given.  Allman 
(’62,  pp.  518-519)  and  Chun  (’80,  p.  195)  attributed  this  phenom- 
enon in  Beroe  to  the  germinal  cells  lying  in  the  walls  of  the  gastro- 
vascular  tubes.  The  supposed  fatty,  phosphorescent  substance 
of  Panceri  according  to  Chun  (’80,  p.  195)  does  not  exist. 
Phosphorescence  was  observed  by  A.  Agassiz  (’74,  p.  371)  in 
embryos. 

The  experiments  described  in  this  paper  also  show  that  this 
property  belongs  to  protoplasm  that  has  but  little  organic  differ- 
entiation, viz:  that  of  the  earlier  stages  of  segmentation.  When 
we  inquire  what  service  in  the  economy  of  the  animal  is  rendered 
in  the  process  of  phosphorescence  we  find  it  difficult  to  give  a 
satisfactory  reply.  I have  never  been  able  to  obtain  phosphor- 
escence in  mature  ctenophores  without  the  motor  activity  of  the 
paddle  plates,  but  not  every  movement  of  these  is  accompanied 
by  phosphorescence.  Darkness  and  mechanical  agitation  are  the 
two  selective  stimuli  whose  joint  presence  results  in  phosphores- 
cence. This  important  fact,  taken  in  connection  with  the  localiza- 
tion of  the  reaction,  the  acceleration  of  its  appearance  by  mechan- 
ical agitation,  and  its  complete  inhibition  by  extremes  of  tempera- 
ture, lead  to  a probable  conclusion  regarding  its  nature.  The 
phosphorescence  of  Mnemiopsis  is  a metabolic  reaction  which  is 
dependent  upon  the  formation  of  a substance  in  darkness,  the 
katabolism  of  which  takes  place  upon  mechanical  stimulation 
and  becomes  observable  as  the  energy  of  light.  The  amount  of 
substance  so  accumulated  may  be  exhausted  by  continued  mechan- 
ical stimulation  in  darkness  or  may  be  consumed  as  produced. 
When  the  animal  is  brought  into  the  light  the  substance  is  no 
longer  produced  or,  if  so,  it  undergoes  katabolic  transformation 
rapidly,  or  the  energy  is  given  out  in  some  other  form  than  light. 
That  the  phosphorescent  substance  cannot  accumulate  in  the 
light  is  shown  by  the  fact  that  ctenophores  removed  from  bright 
daylight  or  sunlight  to  darkness  are  not  immediately  phosphores- 
cent. This  is  the  case  whether  they  have  been  previously  agitated 
or  have  remained  undisturbed. 


PhosphojTscrnce  ni  (Ucnophorcs. 


“5 


SUMMARY. 


1.  riie  dead  matter  originating  from  ctenophores  is  not 
phosphorescent,  /.  c.,  only  living  ctenophores  or  parts  of  them 
phosphoresce. 

2.  Phosphorescence  appears  along  the  rows  of  paddle  plates 
and  no  phosphorescence  was  obtained  from  jelly  free  from  paddle 
plates. 

3.  The  smallest  piece  from  which  phosphorescence  was 
obtained  consisted  of  four  connected  paddle  plates. 

4.  Movement  of  the  paddle  plates  is  not  always  accompanied 
by  phosphorescence. 

5.  No  phosphorescence  was  obtained  from  the  excised 
auricles  having  cilia  but  no  paddle  plates. 

6.  The  sense-organ  is  not  phosphorescent. 

7.  Phosphorescence  does  not  depend  upon  correlation  of  the 
part  with  the  sense  organ.  The  sensory-motor  circuits  for  phos- 
phorescence are  local  in  character. 

8.  No  phosphorescence  could  be  obtained  from  the  eggs  of 
Mnemiopsis  before  segmentation. 

9.  The  early  cleavage  stages  (without  cilia)  are  phosphores- 


cent. 

10.  Gastrulae  (ciliated)  are  phosphorescent,  as  are  also  all 
stages  in  which  paddle  plates  are  present. 

11.  The  phosphorescence  of  embryos  is  easily  exhausted. 

12.  The  deposition  of  eggs  can  be  retarded  by  light. 

13.  Direct  sunlight  prevents  the  appearance  of  phosphores- 
cence, but  in  darkness,  the  power  to  phosphoresce  upon  stimula- 
tion, is  acquired. 

14.  Direct  sunlight  inhibits  a previously  acquired  power  to 
phosphoresce.  Diffuse  daylight  of  sufficient  intensity  has  the 
same  effect. 

15.  Phosphorescence  has  a proportionate  relation,  in  a nega- 
tive sense,  to  the  intensity  of  light. 

16.  Mechanical  stimulation  accelerates  the  appearance  of 
phosphorescence  in  darkness. 

17.  Non-phosphorescent  ctenophores  do  not  become  phos- 
phorescent by  mechanical  agitation  alone. 

18.  Long-continued  mechanical  stimulation  reduces  the  inten- 
sity of  phosphorescence  but  does  not  easily  inhibit  the  phenomenon 
entirely. 


A 7710  s fV.  Peters. 


1 16 

19.  Darkness  accompanied  by  mechanical  stimulation  is  at 
least  one  combination  of  conditions  which  produces  phosphores- 
cence, but  these  two  factors  acting  singly  cannot  produce  this 
result. 

20.  The  phenomenon  of  phosphorescence  was  observed  at 
temperatures  ranging  from  about  (f  C.  to  37°  C.,  with  an  optimum 
at  or  near  2i°.5  C.,  the  temperature  of  the  sea-water. 

21.  The  intensity  of  phosphorescence  diminishes  as  physiologi-  • 
cal  extremes  of  temperature  are  approached. 

22.  The  phosphorescence  of  Mnemiopsis  is  probably  a meta- 
bolic reaction  which  is  dependent  upon  the  formation  of  a sub- 
stance in  darkness  the  katabolism  of  which  takes  place  upon 
mechanical  stimulation  and  becomes  evident  to  observation  as  the 
energy  of  light. 


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24  : 115-140.  4 pis.  Jul.,  1893. 

37.  Davenport,  C.  B.  — Stmlies  in  Morphogenesis. — I.  On  the  Development  of  the 

Cerata  in  JEolis.  B.  M.  C.  Z.  24  : 141-148  . 2 pis.  Jul.,  1893. 

38.  Woodworth,  W.  McM.  — A Method  of  Orienting  small  Objects  for  the  Microtome. 

B.  M.  C.  Z.  25  : 4.5-47.  Dec.,  1893. 

39.  Kofoid,  C.  A.  — On  some  Laws  of  Cleavage  in  Limax.  P.  A.A.  2»:  180-203. 

2 pis.  1894. 

4i».  Davenport,  C.  B.  — Studies,  etc.  — 11.  Regeneration  in  Obelia  and  its  Bearing  on 
DiHerentiation  in  the  Germ-Plasma.  Anat.  Anz.  0 : 283-294.  6 tigs.  Feb.  15, 

1894. 

41.  Holbrook,  A.  T.  — The  Origin  of  the  Endocardium  in  Bony  Fishes.  B.  M.  C.  Z. 

25  : 75-97  . 5 pis.  Aug.,  1894. 

42.  Castle,  W.  E.  — On  the  Cell  Lineage  of  the  Ascidian  Egg.  A Preliminary  Notice. 

P.  A.  A.  20  : 200-216.  2 pis.  Oct.,  1894. 

43.  Weysse,  a.  W.  — On  the  Blastodermic  Vesicle  of  Sus  scrofa  domesticus.  P.  A.  A. 

20  : 283-323.  4 pis.  Dec.,  1894. 

44.  Wilcox,  E.  V.  — Spermatogenesis  of  f’aloptenus  femur-rubrum.  Preliminary 

Notice.  Anat.  Anz.  lO  : 303,  304.  Dec.  19,  1894. 

45.  Miller,  Gerrit  S.,  Jr. — On  the  Introitus  Vagiiue  of  certain  Muridas.  P.  B.  S.  N.  11. 

20  : 459-468.  1 pi.  Feb.,  1895. 

40.  Davenport,  C.  B.,  and  Castle,  W.  E.  — Studies,  etc.  — III.  On  the  Acclimatiza- 

tion of  Organisms  to  High  Temperatures.  Arch.  f.  Entwickelungsmechanik  2: 
227-249.  Jul.  23,  1895. 

47.  Wilcox,  E.  V.  — Sjiermatogenesis  of  Caloptcnus  femur-rubrum  ami  Cicada  tibicen. 

B.  M.  (;.  Z.  2T  : 1-32.  5 pis.  May,  1895. 

48.  Kofoid,  C.  A.  — On  the  Early  Development  of  Limax.  B.  M.  C.  Z.  27 : 33-118. 

8 pis.  Aug.,  1895. 


3 


49.  Nickeumon,  W.  S.  — On  SticlKX'ot ylo  iirpliropis  ( !uMiiii\frli!iin,  a Parasite  of  tlio  Ameri- 

can Pobstor.  Zool. -lalu  l).,  f.  Aiiat.  H : 4I7-4HO.  pis.  IS'Jf). 

50.  DAVKNi'oin',  1?.  — Studies,  c(c.— IV.  A preliminary  Vatalofiiie  of  (lie  Processes 

concerned  in  Ontogeny.  H.  M.  (’.  Z.  27  ; 171-199.  01  figs,  in  text.  Nov.,  1H9.'). 

51.  Paukeu,  O.  11.,  AND  Fi.oyi),  Iv.  — Tlic  Preservation  of  Mammalian  Brains  by  Means 

of  Formol  and  Alcohol.  Anat.  Anz.  II  : 1.56-1.58.  Sept.  ‘28,  189.5. 

52.  Casti-k,  W.  E.  — Tlie  Early  Embryology  of  Ciona  intestinali.s,  Flemming  (L.). 

B.  M.  (’.  Z.  27  : 201-‘280.  13  pis.  \jan.,'  1896. 

53.  Davenport,  B.,  AND  Neal,  II.  V.  — Studies,  etc.  — V.  On  the  Ae<dimatization 

of  Organisms  to  Poisonous  Ohcmical  Substances.  Arch.  f.  Entwickelnngsme- 
cbanik  2:  564-583.  3 figs.  Jan.  28,  1896. 

54.  Parker,  (1.  II.,  and  Eloyd,  R.  — Formaldcbyde,  Formaline,  Formol,  and  Forma- 

losc.  Anat.  Anz.  II  : 567,  568.  Feb.  14,  1896. 

55.  Parker,  G.  II. — The  Reactions  of  Metridium  to  Food  and  otlier  Substances. 

B.  M.  C.  Z.  2«  ; 105-119.  Mar.,  1896. 

56.  Gerould,  J.  II.  — The  Anatomy  and  Histology  of  Caudina  arenata  Gould. 

P.  B.  S.  N.  II.  27  : 7-74.  8 pis.  and  B.  M.  C.  Z.  2«:  1*21-190.  8 pis.  Apr., 

1896. 

57.  Parker,  G.  II.  — Variations  in  the  Vertebral  Column  of  Necturus.  Anat.  Anz.  1 1 : 

711-717.  2 figs.  Mar.  29,  1896. 

58.  Wilcox,  E.  V.  — Further  Studies  on  the  Spermatogenesis  of  Caloptenns  femur- 

rubrum.  B.  M.  C.  Z.  2«  : 191-206.  3 pis.  Jnn.,  1896. 

59.  Mayer,  A.  G.  — The  Development  of  the  Wing  Scales  and  their  Pigment  in  Butt(  r- 

flies  and  Moths.  B.  M.  C.  Z.  20:  207-2.36.  7 pis.  Jun.,  1896. 

60.  Folsom,  J.  W.  — Neelus  murinus,  representing  a new  Thysanuran  Family.  Psyche, 

7 : 391,392.  1 pi.  Jun.,  1896 

61.  Goto,  S.  — Vorlaufige  Mittheilung  fiber  die  Entwicklung  des  Seesteriies  Asterias 

pallida.  Zool.  Anz.  lO  : 271-273.  Jun.  15,  1896. 

62.  Parker,  G.  II.  — Pigment  Migration  in  the  Eyes  of  Palaenionetes.  A Pi-eliminary 

Notice.  Zool.  Anz.  lO:  281-284.  2 figs.  Jun.  29,  1896. 

63.  Woodworth,  W.  McM.  — Preliminary  Report  on  Collections  of  Turbellaria  from 

Lake  St.  Clair  and  Charlevoix,  Michigan.  Bull.  Michigan  Fish  Commission, 
No.  « : 94,  95.  1896. 

64.  Goto,  S.  — Preliminary  Notes  on  the  Embryology  of  the  Starfish  (Asterias  pallida). 

P.  A.  A.  21 : 3-3.3-335.  Jul.,  1896. 

65.  Woodworth,  W.  McM. — Report  on  the  Turbellaria  collected  by  the  Michigan 

State  Fish  Commission  during  the  Summers  of  1893  and  1894.  B.  INI.  C.  Z.  2t> : 
237-244.  1 pi.  Jun.,  1896. 

66.  Tower,  W.  L. — On  the  Nervous  System  of  Cestodes.  Zool,  An/,.  Ill:  323-327. 

2 figs.  Jul. ‘20,  1896. 

67.  Daventort,  Gertrude  C.  — The  Primitive  Streak  and  Notochordal  Canal  in  Che- 

lonia.  Radclitfe  Coll.  Monographs,  No.  8,  54  pp.  11  pis.  [Sept.],  1896. 

68.  Lewis,  Margaret.  — Centrosome  and  Sphere  in  Certain  of  the  Nerve  Cells  of  an 

Invertebrate.  Anat.  Anz.  12  : 291-299.  11  figs.  Sept.  2,  1896. 

69.  Judd,  S.  D.  — Description  of  three  Species  of  Sand  Fleas  (Amphipods)  collected  at 

Newport,  Rhode  Island.  Proc.  U.  S.  Nat.  Mus.  IH  : 593-603.  11  figs.  Aug.,  1896. 

70.  Jennings,  II.  S.  — The  Early  Development  of  Asplanclma  Ilerrickli  de  Guerne. 

A Contribution  to  Developmental  Mechanics.  B.  M.  C.  Z.  20  : 1-118.  10  pis. 

Oct.,  1896. 

71.  Neal,  II.  V.  — A Summary  of  Studies  on  the  Segmentation  of  the  Nervous  System 

ill  Squalus  acauthias.  A Preliminary  Notice.  Anat.  Anz.  12;  377-391.  6 figs. 
Oct.  20,  1896. 

72.  Davenport,  C.  B.,  AND  Cannon,  W.  B.  — On  the  Determination  of  the  Direction 

and  Rate  of  Movement  of  Organisms  by  Light.  Jour,  of  Physiol.  21 : 22-32. 
1 fig.  Feb.  5,  1897. 

73.  Davenport,  C.  B.,  AND  Bullard,  C.  — Studies,  etc.  — VI.  A Contribution  to  the 

(Quantitative  Study  of  Correlated  Variation  and  the  Comparative  Variability  of  the 
Sexes.  P.  A.  A.  22  : 87-97.  Dec.,  1896. 


4 


74.  JNIayeu,  a.  G.  — On  the  Color  iiiul  Color-Patterns  of  Moths  and  Butterflies. 

B.  M.  C.  Z.  :t<>  : ir)7-25o.  in  pis.  Feh.  [Mar.] , 18't7  o/tr/  J‘.  B.  H.  N.  H.  27: 
in  pis.  -Mar.,lH97. 

75.  Pakkku,  ('•  II.  — The  Mesenteries  and  Siphonof^lyphs  in  Metridiuin  inarginatuin 

Milne-Edwards.  B.  M . C.  Z.  20  : 257-272.  1 pi.  Mar.,  1897. 

76.  Pakkkk,  G.  II.  — Photonieehanieal  Chaiifies  in  the  lletinal  Pigment  CA-lls  of  Palae- 

nioneles,  and  their  Uelation  to  the  Central  Nervous  System.  B.  M.  ( '.  Z.  20  : 
27:5-:3no.  l pi.  Apr.,  1897. 

77.  Bunkeu,  F.  S.  — ( )n  the  Structure  of  the  Sensory  Organs  of  the  Lateral  Lim;  of 

Ameiurus  nehitlosus  Le  Sueur.  Anat.  Anz.  12  : 256-269.  Mar.  6,  1897. 

78.  WooDWOUTii,  W.  McM.  — On  a Method  of  Graphic  Reconstruction  from  Serial  Sec- 

tions. Zeit.  f.  wiss.  Mikr.  11;  15-18.  Jul.,  1897. 

79.  Buewsteu,  E.  T.  — a Measure  of  Variability,  and  the  Relation  of  Individual  Varia- 

tions  to  Specific  Ditlerences.  P.  A.  A.  22:269-280.  May,  1897. 

80.  Davenport,  C.  B.  — The  Role  of  Water  in  Growth.  P.  B.  S.  N.  II.  2>8  : 78-84. 

Jun.,  1897. 

81.  Lewis,  Margaret.  — Clyinene  producta  sp.  nov.  P.  B.  S.  N.  II.  2«  : 111-115,  2 pis. 

Aug.,  1897. 

82.  Porter,  J.  F.  — Two  new  Gregarinida.  Jour.  Morph.  11 : 1-20.  8 pis.  Jim.,  1897. 

83.  Woodworth,  W.  McM.  — Contributions,  etc. — II.  On  some  Turhellaria  from 

Illinois.  B.  M.  C.  Z.  21  : 1-16.  1 pi.  Oct.,  1897. 

84.  Porter,  J.  F.  — Trichonymjiha,  and  other  Parasites  of  Termes  tlavipes.  B.  M . C.  Z. 

21  : 45-68.  6 pis.  Oct.,  1897. 

85.  Waite,  F.  (h  — Variations  in  the  Brachial  and  Lumho-Sacral  Plc.xi  of  Necturus 

inaculosus  Ralinesque.  B.  M.  C.  Z.  21 : 69-92.  2 pis.  Nov.,  1897. 

86.  Davenport,  C.  B.,  and  Perkins,  Helen.  — A Contribution  to  the  Study  of  Geo- 

taxis in  the  Higher  Animals.  Jour,  of  Physiol.  22  : 99-110.  Sept.  1,  1897. 

87.  Parker,  G.  II.,  and  Tozier,  C.  II.  — The  Thoracic  Derivatives  of  the  Postcaialinal 

^'eins  in  Swine.  B.  M.  C.  Z.  21  : 131-144.  5 figs.  Mar.,  1898. 

88.  Goto,  S. — The  IMetamorphosis  of  Astcrias  pallida,  with  Special  Reference  to  the 

Fate  of  the  Body  Cavities.  Jour.  Coll.  Sci.,  Tokyo,  lO  : 2:39-278.  6 pis.  1898. 

89.  Neal,  11.  V.  — The  Segmentation  of  the  Nervous  System  in  Sipialus  aeanthias. 

A Gontrilmtion  to  the  Morphology  of  the  Vertclirate  Head.  B.  M.  C.  Z.  21: 
145-294.  9 pis.  May,  1898. 

90.  Lewis,  Margaret.  — Studies  on  the  Central  and  Peripheral  Nervous  Systems  of 

two  Pol^'chaete  Annelids.  I’.  A.  A.  22  : 22:3-268.  8 pis.  Apr.,  1898. 

91.  Hamaker,  J.  1.  — The  Nervous  System  of  Nereis  virens  Sars.  A Studv  in  Com- 

parative Neurology.  B.  31.  C.  Z.  22  : 87-124  . 5 pis.  Jun.,  1898. 

92.  Field,  W.  L.  W.  — A Contrihution  to  the  Study  of  Individual  Variation  in  the 

Wings  of  Lepidoptera.  P.  A.  A.  22  : 389-396.  5 figs.  Jun.,  1898. 

93.  Mark,  E.  L.  — Preliminary  Report  on  Branehiocerianthus  nrccolus,  A new  Type  of 

Actinian.  B.  31.  C.  Z.  22  : 14.5-154.  3 pis.  Aug.,  1898. 

94.  Sargent,  P.  E.  — The  Giant  (ianglion  Cells  in  the  Spinal  Cord  of  Ctenolahrus 

coeru  eus.  Anat.  Anz.  l.>;  212-225.  10  figs.  Dec.  20,  1898. 

95.  Rand,  H.  3V".  — Regeneration  and  Regulation  in  Hydra  viridis.  Arch.  Entwickel- 

ungsmechanik,  S : 1-34.  4 pis.  Feh.  21,  1899. 

96.  Folsom,  J.  W. — The  Anatomy  and  Physiology  of  the  3Iouth-Parts  of  the  Collem- 

holan,  Orchesella  cincta  L.  B.  M.  C.  Z.  2.'>  : 5-:39.  Jul.,  1899. 

97.  31ark,  E.  L.  — “ Brancliiocerianthus,”  a Correction.  Zool.  Anz.  22  : 274  , 275. 

Jun.  26,  1899. 

98.  Bancroft,  F.  W.  — Ovogenesis  in  Distaplia  occidentalis  Ritter  (ms.),  with  Remarks 

on  Otlier  Species.  B.  31.  C.  Z.  2.-»  : 57-112.  6 pis.  Oct.,  1899. 

99.  Galloway,  T.  W. — Observations  on  Non-sexual  Reproduction  in  Dero  vaga 

B.  M.  C.  Z.  25  : 11:3-140.  5 pis.  Oct.,  1899. 

100.  Parker,  G.  H.  — The  Photomechanical  Changes  in  tlie  Retinal  Pigment  of  Gaiu- 

marus.  B.  M.  C.  Z.  25  : 141-148.  1 pi.  Oct.,  1899. 


5 


101.  Pahkicr,  (1.  11. , AND  Davis,  Fhrdbuioa  K.  — Tho  Blood  VchhcIh  of  the  Heart  in 
('lUTlmrias,  Riijii,  and  Aiuia.  I*.  B.  S.  N.  II.  20(8);  108-178.  3 pis.  Oct.,  181)9. 
10‘J.  Uand,  II.  W.  — Tlio  Uef^ulatioii  of  (J raft  AbnonnaliticH  in  Ilyilra.  Arch.  f.  En- 
twickohinf?sinochanik,  0(2):  101-214.  I'ls.  5-7.  Dec.,  1899. 

103.  Ykkkes,  K.  AI.  — Reaction  of  Entoinostraca  to  Stimulation  by  Tiif^llt.  Amcr. 

Jour,  rhysiol.  ;j(4):  157-182.  Nov.,  1899. 

104.  Tower,  W.  L.  — The  Nervous  System  of  the  Cestode  Moniezia  expansa.  Zool. 

Jalirb.,  Abtb.  f.  Anat.  i;t(3);  359-384.  Pis.  21-20.  Apr.  10,  1900. 

105.  Waite,  F.  C. — The  Structure  and  Development  of  the  Antennal  Glands  in  llomarus 

americanus  Milne-Edwards.  B.  M.  C.  Z.  ;8.">(7);  149-210.  6 pis.  Dec.,  1899. 
100.  Sargent,  P.  E.  — Rcissner’s  Fibre  in  the  Canalis  Centralis  of  Vertebrates.  Anat. 
A nz.  17(2-3):  33^4.  3 pis.  Jan.  15,  1900. 

107.  Williams,  S.  B.  — The  Specific  Gravity  of  Some  Fresh-Water  Animals  in  Relation 

to  their  Habits,  Development,  and  Composition.  Amer.  Nat.  514(398):  95-108. 
3 figs.  Feb.,  1900. 

108.  Castle,  W.  E.  — The  Metamerism  of  the  Hirudinea.  P.  A.  A.  515(15):  283-303. 

8 figs.  Feb.,  1900. 

109.  Linville,  H.  R.  — Maturation  and  Fertilization  in  Pulmonate  Gasteropods. 

B.  M.  C.  Z.  515(8):  211-248.  4 pis.  May,  1900. 

110.  Parker,  G.  II.  — Note  on  the  Blood  Vessels  of  the  Heart  in  the  Sunfish  (Orthag- 

oriscus  mola  Linn.).  Anat.  Anz.  17(16-17):  313-316.  1 fig.  3Iar.  31,  1900. 

111.  Pratt,  II.  S.  — The  Embryonic  History  of  Imaginal  Discs  in  Melophagus  ovinus  L., 

etc.  P.  B.  S.  N.  H.  20(13):  241-272.  7 pis.  June,  1900. 

112.  Castle,  W.  E.  — Some  North  American  Fresh-Water  Rhynchobdellidae,  and  their 

Parasites.  B.  M.  C.  Z.  510(2):  15-64.  8 pis.  Aug.,  1900. 

113.  Bowers,  Mary  A. — Peripheral  Distribution  of  the  Cranial  Nerves  of  Spelerpes 

bilineatus.  P.  A.  A.  510(11):  177-193.  2 pis.  Oct.,  1900. 

114.  Folsom,  J.  W.  — The  Development  of  the  Mouth-Parts  of  Anurida  maritima  Gudr. 

B.  M.  C.  Z.  510(5);  85-157.  8 pis.  Oct.,  1900. 

115.  Parker,  G.  H.,  and  Burnett,  F.  L.  — The  Reactions  of  Planarians,  with  and  with- 

out Eyes,  to  Light.  Amer.  Jour.  Physiol.  4(8);  373-385.  4 figs.  Dec.,  1900. 

116.  Yerkes,  R.  M.  — Reaction  of  Entoinostraca,  etc.  II.  Reactions  of  Daphnia  and 

Cypris.  Amer.  Jour.  Physiol.  4 (8):  405-422.  6 figs.  Dec.,  1900. 

117.  Galloway,  T.  W.  — Studies  on  the  Cause  of  the  Accelerating  Ellect  of  Heat  upon 

Growth.  Amer.  Nat.  514(408):  949-957.  6 figs.  Dec.,  1900. 

118.  Parker,  G.  II.  — Correlated  Abnormalities  in  the  Scutes  and  Bony  Plates  of 

the  Carapace  of  the  Sculptured  Tortoise.  Amer.  Nat.  515  (409);  17-24.  5 figs. 
Jan.,  1901. 

119.  Yerkes,  R.  M.  — A Study  of  Variation  in  the  Fiddler  Crab  Gelasimus  pugilator 

Latr.  P.  A.  A.  510(24):  415-442.  3 fig.s.  Apr.,  1901. 

120.  Parker,  G.  H.,  and  Arkin,  L.  — The  Directive  Influence  of  Light  on  the  Earth- 

worm Allolobophora  foetida  (Sav.).  Amer.  Jour.  Physiol.  5(3):  151-157.  1 fig. 
Apr.,  1901. 

121.  Strong,  R.  M.  — A Quantitative  Study  of  Variation  in  the  Smaller  North-American 

Shrikes.  Amer.  Nat.  515  (412);  271-298.  8 figs.  Apr.,  1901. 

122.  Sargent,  P.  E. — The  Development  and  Function  of  Reissner’s  Fibre,  and  its 

Cellular  Connections.  P.  A.  A.  30(25):  443-452.  2 pis.  Apr.,  1901. 

123.  Prentiss,  C.  W.  — The  Otocyst  of  Decapod  Crustacea;  Its  Structure,  Develop- 

ment, and  Functions.  B.  M.  C.  Z.  510(7):  165-251.  10  pis.  July,  1901. 

124.  Peters,  A.  W.  — Some  Methods  for  Use  in  the  Study  of  Infusoria.  Amer.  Nat. 

515(415):  5.5.3-559.  2 figs.  July,  1901. 

125.  Prentiss,  C.  W.  — A Case  of  Incomplete  Duplication  of  Parts  and  Apparent  Regu- 

lation in  Nereis  virens  Sars.  Amer.  Nat.  515(415):  563-574.  6 figs.  July,  1901. 


6 


126.  Rand,  H.  W.  — The  Regenerating:  Nervous  System  of  Lumbricidae  and  the  Cen- 

trosornc  of  its  Nerve  Cells.  B.  M.  C.  Z.,  :87(3)  : 83-164.  8 pis.  Sept.,  1901. 

127.  Frandsen,  P.  — Studies  on  the  Reactions  of  Liinax  niaximus  to  Directive  Stimuli. 

P.  A.  A.,  ;8T(8)  : 183-227.  22  figs.  Oct.,  1901. 

128.  Yerkes,  R.  M.  — A Contribution  to  the  Nervous  System  of  Gonionemus  murbachii. 

Pt.  I.  Amer.  Jour,  of  Physiol.,  «(6)  : 434-449.  Feb.,  1902. 

129.  Oppenheimer,  a.  — Certain  Sense  Organs  of  the  Proboscis  of  the  Polychaetous 

Annelid  Rhynchobolus  dibranchiatus.  P.  A.  A.,  : 551-569.  6 pis. 

Apr.,  1902. 

130.  Williams,  S.  R.  — Changes  Accompanying  the  Migration  of  the  Eye  and  Obser- 

vations on  the  Tractus  opticus  and  Tectum  o})ticum  in  Pseudopleuronectes 
americanus.  B.  M.  Z.  C.,  *<>(1)  : 1-57.  5 pis.,  7 figs.  May,  1902. 

131.  Yerkes,  R.  M.  — A Contribution  to  the  Nervous  S\"stem  of  Gonionema  murbachii. 

Pt.  II.  Amer.  Jour,  of  Physiol.,  7(2) : 181-198.  May,  1902. 

132.  Bigelow,  M.  A.  — The  Early  Development  of  Lepas.  A Study  of  Cell-Lineage 

and  Germ-Lajmrs.  B.  M.  C.  Z.,  40(2)  : 59-144.  12  pis.  July,  1902. 

133.  Parker,  G.  IT.  — Notes  on  the  Dispersal  of  Sagartia  luciae  Verrill.  Amer.  Nat., 

:{«(426)  : 491-493.  June,  1902. 

134.  Howe,  F.,  Jr.  — A Case  of  Abnormality  in  Cats’  Paws.  Amer.  Nat.,  ;iO(427)  : 

511-526.  18  figs.  July,  1902. 

135.  Strong,  R.  ISI. —The  Development  of  Color  in  the  Definitive  Feather.  B.  M.C.  Z., 

40(3)  : 145-185.  9 pis.  Oct.,  1902. 

136.  Castle,  W.  E.  — Mendel’s  Law  of  Heredity.  P.  A.  A.,  :5«(18)  : 533-548.  Jan.,  1903. 

137.  Castle,  W.  E.  — The  Heredity  of  Sex.  B.  M.  C.  Z.,  40(4)  : 187-218.  Jan.,  1903. 

138.  Parker,  G.  H.  — The  Optic  Chiasma  in  Teleosts  and  its  Bearing  on  the  Asymmetry 

of  the  Heterosomata  (Flat  Fishes) . B.M.C.Z.,  40(5)  ; 219-242.  Ipl.  Jan., 1903. 

139.  Mark,  E.  L.  — A Pai-affine  Bath  heated  by  Electricity.  Amer.  Nat.,  37(4.34)  : 

115-119.  3 figs.  Febr.,1903. 

140.  Adams,  G.  P.  — On  the  Negative  and  Positive  Pliototropism  of  the  Earthworm 

vMlolobophora  feetida  (Sav.)  as  determined  by  Light  of  Diflerent  Intensities. 
Amer.  Jour,  of  Physiol.,  0(1)  : 26-34.  2 figs.  Mar.,  1903. 

141.  Prentiss,  C.  W.  — Polydactylism  in  IMan  and  the  Domestic  Animals,  with  esi>ecial 

Reference  to  Digital  V^ariations  in  Swine.  B.M.C.Z.,  40(6)  ■ 243-314.  22  pis. 
and  26  figs.  Apr.,  1903. 

142.  Castle,  W.  E.,  and  Allen,  G.M.  — The  Heredity  of  Albinism.  P.A.A.,  :t^<(21)  : 

601-622.  Apr.,  1903. 

143.  Parker,  G.  H.  — The  Skin  and  the  Eyes  as  Receptive  Organs  in  the  Reactions  of 

Frogs  to  Light.  Amer.  Jour,  of  Physiol.,  10(1)  : 23-36.  Sept.,  1903. 

144.  Howard,  A.  D.  — On  the  Structure  of  the  Outer  Segments  of  the  Rods  in  the 

Retina  of  Vertebrates.  Amer.  Nat.,  37(440)  : 541-550.  Sept.,  1903. 

145.  Breed,  R.  S.  — The  Changes  which  occur  in  the  Muscles  of  a Beetle,  Thymalus 

marginicollis  Chevr.,  during  Metamorphosis.  B.M.C.Z.,  40(7)  : 315-382.  7 pis. 
Oct.,  1903. 

146.  Castle,  W.  E.  — The  Laws  of  Heredity  of  Gallon  and  Mendel,  and  Some  Laws 

Governing  Race  Improvement  by  Selection.  P.A.A.,30(8)  : 221-242.  Nov.  1903. 

147.  Carlton,  F.  C.  — The  Color  Changes  in  the  Skin  of  the  so-called  Florida  Chameleon, 

Anolis  carolinensis  Cuv.  P.A. A.,  30(10)  : 257-276.  Ipl.  Dec. , 1903. 

148.  Lander,  C.  IT. — The  Anatomy  of  Hemiurus  crenatus  (Rud.)  Liihe,  an  Appen- 

diculate  Trematode.  B.M.C.Z.,  45(1)  : 1-28.  4 pis.  Jan.,  1904. 

149.  Peters,  A.  W.  — Metabolism  and  Division  in  Protozoa.  P.A.A.,  30(20)  : 439-516. 

Apr.,  1904. 

150.  Hall,  R.  W.  — The  Development  of  the  Mesonephros  and  tlie  Mullerian  Duct  in 

the  Amphibia.  B.M.C.Z.,  45(2)  : 29-125.  8 pis.  June,  1904. 


rONTUIlUTTIONS  KliOM  TllK  Z(){)L()(JICAL  LAHOKATORV  OF 
TIIK  MUSEUM  OF  COMPARATIVE  ZOIH.OOY  AT  HARVARD 
COLLEGE.  ( Continued.) 

151.  Bigklow,  II.  11.  — Tlie  Sense  of  lleariiifr  in  tlio  Goldfisli  ('iiriissins  aunitus  \j. 

Aincr.  Naf.,  :tN(448):  275-*284.  Apr.  [June],  1904. 

15'2.  Allkn,  G.  M.  — Tlie  Ileredif}’ of  ('oat  (\)lor  in  Mice.  I*.  A.  A.,  10(2):  59-10.3. 
July,  1904. 

153.  Sargent,  P.  PL — The  Optic  Reflex  Apparatus  of  Vertebrates  for  Sliort-cireuit 

Transmission  of  Motor  Reflexes  through  Reissuer’s  Fibre;  its  Mori)hology, 
Ontogeny,  Phylogeny,  and  Function. — Part  I.  Tlie  Fish-like  Vertebrates. 
R.M.C.Z  , l.-»(3):  127-259.  11  pis.  July,  1904. 

154.  Mast,  S.  O.  — A Simple  Apparatus  for  aerating  Liquid  Solutions.  Amer.  Nat., 

(453)  : 655-660.  Sept.  [Oct.],  1904. 

155.  Parker,  G.  II.,  and  Starratt,  S.  A.  — The  Effect  of  Heat  on  the  Color  Changes 

in  the  Skin  of  Anolis  earolinensis  Cuv.  P.  A.  A.,  40(10);  45-5-466.  Nov.,  1904. 

156.  Rand,  II.  W.  — The  Behavior  of  the  Epidermis  of  the  Earthworm  in  Regeneration. 

Arch.  f.  Entwickelungsmechanik,  10(1)  : 16-57.  Taf  1-3.  Feb.,  1905. 

157.  Smallwood,  W.  M.  — The  Maturation,  Fertilization,  and  Early  Cleavage  of 

Haminea  solitaria  (Say).  B.IM.C.Z.,  15(4)  : 259-318.  13  pis.  Dec.,  1904. 

158.  Castle,  W.  E.  — Heredity  of  Coat  Characters  in  Guinea-Pigs  and  Rabbits.  Publ. 

Carnegie  lust.  Washington,  No.  23.  78  pp.  6 pis.  Febr.,  1905. 

159.  Parker,  G.  H.  — The  Reversal  of  Ciliary  Movement  in  Metazoans.  Amer.  Jour. 

of  Physiol.,  i;S(l)  : 1-16.  Febr.,  1905. 

160.  PETRUNKf:viTCH,  A.  — Natural  and  Artificial  Parthenogenesis.  Amer.  Nat., 

SO (458)  : 65-76.  Febr.  [Mar.],  1905. 

161.  Smith,  G.  — The  Effect  of  Pigment-Migration  on  the  Phototropism  of  Gammarus 

annulatus  S.  I.  Smith.  Amer.  Jour,  of  Physiol.,  IS (3)  ; 205-216.  Apr.,  1905. 

162.  Carpenter,  F.  W.  — The  Reactions  of  the  Pomace  Fly  (Drosophila  ampelophila 

Loew)  to  Light,  Gravity,  and  Mechanical  Stimulation.  Amer.  Nat.,  SO(459)  : 
156-171.  Apr.,  1905. 

163.  Peters,  A.  W.  — Phosphoi-escence  in  Ctenophoi’es.  .Jour,  of  Exp.  Zodl.,  2(1); 

103-116.  Apr.,  1905. 


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r 


UNIVERSITY  OF 


ILLINOIS-URBANA 


593.8P44  C001 

PHOSPHORESCENCE  IN  CTENOPHORES 


